Study On The Dynamics Of Carbon Sinking In Oligostachyum Scabriflorum Forest

Oligostachyum scabriflorum,a species of bamboo belonged to Oligostachyum,had the biggest cultivated and reclaimed area among all species of this genus.Oligostachyum scabriflorum not only brought more benefits to the local farmers,but also played a very important role in maintaining ecological balance.Dynamics of carbon absorption and emission of Oligostachyum scabriflorum forest were measured in Sangxi village,Hongtian town,Yongan county,and the existing biomass,carbon concentration,carbon density,carbon storage and carbon emission were analyzed detailedly in 1a period.The dynamic characteristics of carbon balance were found out..The research results would provided references for studying and management of carbon bank dynamics in bamboo forest ecosystem.The results were as follows:(1) The results from the study of the intemporal and spatial distribution of individual biomass and carbon storage(carbon density) had shown that the rule of individual biomass growth was much similar to the individual carbon storage and carbon density dynamics in different growth stages.The growth rates of entire forest biomass and carbon storage were in the following order: mid-slope＞below-slope＞up-slope.In terms of the growth rate of individual biomass and carbon storage,the rule of carbon storage was almost similar to the changes of biomass from the shoots to young bamboo and new bamboo.The bamboo stalks were in the status of net accumulation before midperiod of 3a,then turned into the status of net loss.The bamboo rhizomes were in the status of net accumulation before later period of 3a,then turned into the status of net loss.(2) Based on eight kinds of common growth equations,the dynamic models of individual biomass,carbon storage and carbon density were builded.The laws of the biomass and carbon accumulation coincided with Logistic and Gompertz model.Their fitting effects were the best.(3) Connection of different age's individuals at the same year were taken for the total life process(mature bamboo:1a-4a;rhizome:new rhizome-5a).The fitting of individual biomass and carbon storage(carbon density) showed that the accumulation laws of biomass and carbon of mature bamboo stalk and rhizome fit Rолясрmodel.(4) The season and daily changes of net photosynthetic rate and soil respiratory rate were studied.The daily net photosynthetic rate showed singlet curve with the max value emerging at 10:30-13:30,and the largest value of season change(10.25μmol·m^-2·s^-1) emerged at the growth season(June-August).The daily net soil respiratory rate also showed singlet curve with the max value emerging at 13:30,and the largest value of season change also emerged at the growth season.(5) There were notable differences of carbon sinking function of different organs and different growth phases.Leaves did the largest contribution,and the average annual net sinking storage of leave in Oligostachyum scabriflorum forests in up-slope,mid-slope and below-slope were 14875.01,15072.25,15004.28 kg·ha^-1 respectively,and the average value was 14983.85 kg·ha^-1.Shoot-young bamboo,new bamboo and 1a-2a bamboo were carbon sequestration,3a-4a bamboo were carbon sources.New rhizome-midperiod of 3a rhizome were carbon sequestration, then turning into carbon sources.(6) Estimation of the dynamics of carbon balance showed that the Oligostachyum scabriflorum forest was carbon source.The dynamics of carbon balance in different slopes were distinguishing.The forest in up-slope was carbon sequestration at June-July,that in mid-slope was carbon sequestration at June-September,that in below-slope was carbon sequestration at April-September,and the forests in each slope were carbon sources at other months.The dynamic of carbon sinking were very complex.The carbon sinking processes were very different in different organs and different growth phases,which were the key researching steps. The study of dynamics of carbon sinking in Oligostachyum scabriflorum forest would provided some bases for its management and researching on carbon balance of other bamboo forests.